UK officials worked to halve the time it would take the country to go to war after the Cuban missile crisis, according to newly released documents.
Macmillan ordered a review of the UK's war preparedness plans
Prime Minister Harold Macmillan ordered a review of war preparedness plans following the stand-off, say official documents from the National Archives.
The US-Soviet row over Russian missiles based in Cuba brought the world to the brink of nuclear conflict.
As a result the UK decided to ensure it could be war-ready within two days.
The National Archives published records of a Cabinet meeting which took place in November 1962, a month after the crisis ended.
President John F. Kennedy announces the Cuba blockade during the missile crisis
They reveal urgent work by ministers to make certain war procedures were up to date.
A secret simulation exercise, Operation Felstead, had previously shown that under existing Government powers it would take four days to mobilise forces.
But after the Cuban crisis, there were fears that such arrangements did not offer enough flexibility to counter the threat of a nuclear strike, or to cope quickly with the aftermath.
Minutes of a Cabinet office home defence committe meeting show that officials therefore resolved to halve the preparation time.
The Government decided to rewrite part of the War Book, its guidelines for the countdown to conflict.